Heading into the weekend like... 🧑‍🚀 On February 7, 1984, astronaut Bruce McCandless II became the first human in history to go on a spacewalk without a connection to their spacecraft. McCandless soared outside the space shuttle Challenger with the Manned Maneuvering Unit (MMU), a propulsion device on the back of his spacesuit that used two tanks of hydrogen and 24 nozzles to move him around. In this iconic photo, taken by Challenger pilot Hoot Gibson, McCandless was just a few meters away from the shuttle, but further MMU flights by McCandless and astronaut Robert L. Stewart took them more than 300 feet (91 meters) into space. The MMU was used for several more flights in the 1980s. Today's NASAAstronauts now wear SAFER (Simplified Aid For EVA Rescue), a smaller, simpler thruster system, in case they accidentally become untethered on a spacewalk. Image description: An astronaut, wearing a full spacesuit and a large backpack, floats above Earth. Earth's blue seas and thin white cl...